Last year, the Philadelphia Flyers made a big acquisition at the trade deadline, adding Toronto Maple Leafs forward Kris Versteeg. It paid dividends in their first-round matchup against the Buffalo Sabres, as they scored 19 goals in their four wins; Versteeg had five points in the series. But in the second round, the Flyers ran up against the Boston Bruins -- and they were not prepared for the Bruins' offensive onslaught. The Flyers were swept, allowing 20 goals along the way.
Now, if you looked at the Flyers' regular-season performance, it didn't look like they needed help on defense. After all, they allowed 2.63 goals per contest, which is in the top third of the league.
But the Playoff Power Meter would've told a different story.